1. Technical Field
The present invention relates to a method of manufacturing a color filter substrate, a color filter substrate, a display device and electronic equipment.
2. Related Art
In recent years, development of a so-called color filter on array (COA) structure which is a color filter formed on an array substrate has been carried out. With the COA structure, it is not necessary to align the array substrate on which the color filter is formed with an opposing substrate on which electrodes are formed throughout the surface, so that the manufacturing process can be simplified. In addition, it is possible to freely design a pattern formed on the substrates without considering a positioning error of the substrates because a problem of the alignment accuracy at the time of combining the substrates does not arise. JP-A-2000-314806 is a first example of related art, JP-A-2004-355995 is a second example of related art and JP-A-2004-94206 is a third example of related art. For example, a width of a light shielding layer can be made smaller as described in the first example. This allows a display device to have a high aperture ratio.
As a method of manufacturing a color filter in the color filter on array (COA) structure, a dyeing method, a pigment dispersion method, an electrodeposition method, a film transfer method and the like have been developed. The first example disclosed the following method to form a color filter. First, a transparent conductive film which is patterned in advance is immersed into a solution of water-soluble polymer in which pigments are dispersed. The transparent conductive film is then electrified so that the pigments are electrodeposited on the transparent conductive film.
Other color filter manufacturing method using an ink-jet method has also been studied. In the color filter manufacturing method using the ink-jet method, for example, a mixture of a transparent conductive film material such as indium tin oxide (ITO) and SnO2 and a color filter material such as pigments is patterned so as to form a color filter by a photolithography method or various printing methods.
According to the above-mentioned electrodeposition method, the color filter is formed by electrodepositing the pigments onto the transparent conductive film. This means that each transparent conductive film has to be electrically conductive and this limits layout patterns of the color filter. For example, the color filter can not be separately disposed by each pixel. Furthermore, since a relatively high voltage is applied to the transparent conductive film, a so-called bipolar phenomenon occurs between two adjacent transparent conductive film patterns and colors of the color filter could be mixed. On the other hand, according to the ink-jet patterning method in which the mixture of the transparent conductive film material and the pigments is patterned, a heat treatment that imparts sufficient conductivity to the transparent conductive film cannot be performed because there is a temperature limit due to the decomposition temperature of the pigments. Therefore, a transparent conductive film formed by sputtering had to be used at the same time.